The invention relates to a projector.
WO 2004/029 507 A1 discloses a projector that has an illuminant that is arranged in a projector housing, is capped at one or two ends and comprises a lamp or a burner, for example a discharge lamp in the form of a metal-halide lamp, and a reflector that reflects the light emitted by the illuminant in the direction of a front opening of the projector housing that can be sealed by a transparent cover element, for example a protective disk or lens disk.
In addition to radiating visible light beams, a burning illuminant also produces in its arc or filament invisible thermal radiation that lies in the infrared spectral region and is output by the following three processes to the surroundings of the illuminant:                a) the thermal radiation is partially absorbed by the components surrounding the illuminant, such as reflector, illuminant base and supply leads to the illuminant, and by the projector housing, which components thereby experience negative influence on their material properties and themselves act as secondary heat source,        b) thermal conduction takes place via the electric contacts and via the ceramic bodies of the illuminant base, and        c) the ambient air of the illuminant is heated up, rises upward and entrains cooler air upward from below in a convective cooling process.        
In order to support the last-named process and to provide a projector of high power with a compact design, the projector housing disclosed in WO 2004/029 507 A1 comprises an upper, cylindrical projector housing part and a lower projector housing part that is of cuboidal design and on which ventilation shafts with mutually separate ventilation ducts are arranged. The ventilation ducts are separated from one another by fins that have inside the ventilation shaft a first fin section adjacent to the air exit openings, and a second fin section, which is adjacent to the air exit openings and is bent away from the first fin section.
U.S. Pat. No. 5,172,975 A discloses a projector with an illuminant, a reflector and a light exit opening in a cylindrical projector housing on which there are formed ventilation ducts that likewise circulate for convective cooling of the surroundings of the illuminant outputting heat, and are delimited by fins. The fins are bent away outside the cylindrical projector housing and are flanged at their ends so that, firstly, light is prevented from exiting from the interior of the projector housing and, secondly, the flow of air is directed away perpendicularly from the projector housing.
U.S. Pat. No. 1,758,290 A discloses a projector housing with ventilation shafts, which are arranged on the housing walls, have ventilation ducts separated from one another and are separated from one another by fins such that uniform ventilation ducts are produced via which the cooling air flows into the interior of the projector housing. The ends, projecting into the interior of the projector housing, of the fins above and below the optical axis of the projector are bent away again in respectively opposite directions such that the ends of the fins arranged above the optical axis are directed toward the underside of the projector housing, while the ends, arranged below the optical axis, of the fins are directed toward the top side of the projector housing, and the two sections are connected to one another in a central horizontal part such that improved circulation of cooling air through the projector housing is attained by the different alignment of the ends, located in the interior of the projector housing, of the fins.
EP 0 389 659 A1 discloses a projector in the form of an emitter of compact design that has a lamp capped at one or two ends, a reflector part that comprises an annular frame bracket into which a parabolic reflector is inserted and on whose light exit side holders for a glass disk are arranged, a block-shaped housing for holding heat-sensitive electrical and electronic components, and a cooler that is arranged laterally on the reflector part at the level of the lamp. The cooler has a flange attachment that is aligned in the extent of the lamp axis and which is adjoined outside the reflector part by a cooling surface element that is designed as a cooling fin block, perforated plate arrangement, laminar arrangement or as a spigot configuration. The lamp holder is inserted in effectively thermally conducting contact into the flange attachment of the cooler, which attachment is designed as a tube flange, the cooler projecting with its flange attachment through an opening of the reflector into the reflector interior, while the cooling surface element projects across its entire width over the near side wall of the block-shaped housing such that the air heated in the region of the cooling surface element can flow past the housing and, in the process, the heat output by the lamp by convection can be dissipated to the ambient air via the cooler and pass the block-shaped housing containing the temperature-sensitive electrical and/or electronic components.
U.S. Pat. No. 5,515,254 A discloses a color mixing projector having a housing that is arranged movably in a projector bow-type handle. An illuminant and a cooling device are arranged in a first section of the housing, while a second housing section contains movable color filters and a lens cover. The cooling device comprises a number of contoured, external cooling ribs that are incorporated into the first housing section, which consists of aluminum casting, and have an approximately ellipsoidal outer contour in which an elliptical reflector is arranged and surrounds the illuminant. With the aid of an ellipsoidal cutout, the housing surrounds an illuminant, which is inserted into a mount that is surrounded by an annular cutout of the cooling device. Aligned with the contoured, external cooling ribs are internal cooling ribs that are arranged around an inner annular periphery of an annular section and form a relatively large heat-absorbing surface, while the heat is dissipated via additional ventilation openings. The front termination of the first housing section is formed by a plate that keeps the heat output by the illuminant away from the second, front section of the housing.
EP 0 751 339 discloses an illumination device having a paraboloid-shaped reflector, an illuminant arrangement and a bipartite, tubular front housing in which a front lens is arranged. Provided on the optical axis of the paraboloid-shaped reflector is a central opening for holding the illuminant arrangement, which comprises the illuminant and an illuminant holder made from aluminum casting or ceramic with a number of parallel cooling ribs. The reflector and the front housing consist of an effectively thermally conducting material such as aluminum. The convex rear side of the reflector has a number of parallel cooling ribs that are integrally formed in one piece on the reflector and dissipate the heat output by the illuminant to the surroundings by convection cooling. The illuminant holder, the illuminant, the reflector and the cooling device form a part of the projector housing, the cooling ribs being integrally formed on the outside of the reflector.